GREEN SEATAC PARTNERSHIP URBAN FOREST ENHANCEMENT GUIDE GREEN SEATAC PARTNERSHIP URBAN FOREST ENHANCEMENT GUIDE TABLE OF CONTENTS Executive Summary .................................................................................................................................................................................... 9 1. Introduction .........................................................................................................................................................................................11 The Need for a Green SeaTac Partnership ...........................................................................................................................................12 2. More Than Just Green: Urban Forests Have Many Benefits .........................................................................................14 Economic Benefits ..............................................................................................................................................................................17 Air-Quality Improvements ................................................................................................................................................................17 Water-Quality Improvements ...........................................................................................................................................................17 Mental Health Benefits .......................................................................................................................................................................17 Climate-Change Mitigation ...............................................................................................................................................................18 Decreased Crime .................................................................................................................................................................................18 3. The Challenge: Threats to the Urban Forest.........................................................................................................................19 SeaTac’s Urban Forest ........................................................................................................................................................................19 Challenges and Threats to Sustainability ........................................................................................................................................19 Fragmentation and Development .............................................................................................................................................19 Declining Habitat Quality ......................................................................................................................................................... 20 Invasive Species: Plants and Insects ........................................................................................................................................ 20 Native Vegetation Struggling to Regenerate ............................................................................................................................21 Harmful Use: Intentional and Unintentional ..........................................................................................................................21 Climate Change .......................................................................................................................................................................... 22 Lack of Homeowner Education and Resource Allocation .................................................................................................... 22 Resource Limitations on Urban Forest Management and Maintenance on Public Lands ....................................................... 22 4. Understanding the Challenge in Context ...............................................................................................................................23 Community Engagement Process ....................................................................................................................................................23 Community Survey .....................................................................................................................................................................23 Open Houses ............................................................................................................................................................................... 24 Small Community Meetings ......................................................................................................................................................25 Centering Equity and Diversity .........................................................................................................................................................25 Canopy-Cover Analysis: Canopy Cover in Relation to Schools ........................................................................................... 26 Canopy-Cover Analysis: Canopy Cover in Relation to Public Housing .............................................................................. 26 5. Meeting the Challenge .................................................................................................................................................................. 30 Current Green SeaTac Partnership Members ................................................................................................................................ 30 City of SeaTac .............................................................................................................................................................................. 30 Parks, Community Programs and Services ..................................................................................................................... 30 Port of Seattle.............................................................................................................................................................................. 30 Forterra ........................................................................................................................................................................................ 30 Volunteers and the Community at Large .................................................................................................................................31 Potential Sponsors ..............................................................................................................................................................................31 6. Assessing the Urban Forest .........................................................................................................................................................32 Part I: Land-Cover Classification and Canopy-Cover Analysis ....................................................................................................32 Methods ........................................................................................................................................................................................32 Results ...........................................................................................................................................................................................34 Part II: Parks and Natural Areas Health Assessment ......................................................................................................................34 Methods ........................................................................................................................................................................................34 Tree-iage and the Forest Landscape Assessment Tool ...................................................................................................35 Tree-iage Categories ...........................................................................................................................................................37 Results ...........................................................................................................................................................................................38 Tree-iage Matrix ..................................................................................................................................................................38 Overstory Species ................................................................................................................................................................38 Regenerating Overstory Species .......................................................................................................................................38 Native Understory Species .................................................................................................................................................38 Invasive Species ...................................................................................................................................................................38 Slope ......................................................................................................................................................................................41 7. Moving Forward ..............................................................................................................................................................................